Liquid receptacles such as fish ponds, water-storage reservoirs, tanks and other facilities containing water or aqueous systems may be aerated or agitated by the injection of air or water or an air-water mixture into the liquid within the receptacle. Generally speaking, the pipe system for supplying the fluid and distributing the liquid in the receptacle is a bulky and complex arrangement. Where air and water are to be injected together or through respective nozzles, connections are required for both the air and the water by appropriate fittings which can be connected by hoses, pipes or the like to the air or water sources. The nozzle systems within the receptacle are frequently inaccessible and, in many cases, cannot be changed, replaced or even cleaned with any degree of regularity. Sealing problems arise when the systems must be disassembled for cleaning.
In prior art systems, the nozzles can be inserted from the interior of the receptacle and clamped from the outer side so that for the nozzles respective bores must be provided in the wall of the receptacle and these bores must be sealed.
On the outer side of the receptacle, a T fitting can be mounted, whose shank can be connected to the nozzle and whose cross bar can be connected to the cross bars of other nozzles by appropriate piping and to the source of the fluid to be injected.
Because of the many holes required in the wall and the individual mounting of the nozzles forming the respective orifices, the apparatus is expensive. Because of the need to mount numerous small parts, the mounting operation is time consuming and complex. At each mounting location there is a danger that the seal may be lost because of fluctuations in temperature and varying mechanical stresses and loads which may be applied to the parts. Because of the spatial requirements for the feed and connecting pipelines, the piping must have a relatively small cross section so that the piping is characterized by high flow losses, comparatively noisy operations and limited versatility. For example, if hot water is to be injected, the hot water suffers a substantially greater cooling in piping of small cross section than in piping of larger cross section.
For jet generators which are intended for use in whirlpool baths and the like, there is also a problem of hygiene, especially in the region of the nozzles. In the use of liquid receptacles and especially whirlpool baths, it generally cannot be avoided that contaminants and bacteria collect in the piping systems and create hygiene problems within the receptacle. The earlier systems cannot be readily disassembled for cleaning and if they can be disassembled, cannot be reassembled without the danger of seal deterioration.
German Patent Document DE-A-21 14 534 describes a grate for the finely divided introduction of gases into a bath liquid in a bubbling mode. The bubbling grate comprises grate bars of yieldable material, for example, a plastic synthetic resin, which constitutes the gas distribution system. The method of connection of this grate to the gas source, for example, a pump, is not detailed there.